function cons() {
  this.len = 1;
  this.a = function () {
    console.log('a');
  };
  console.log(this, this.a, this.b);
}

cons.b = function () {
  console.log('b');
};

// normal
console.log(cons);
cons.b();
cons();
console.log('len: ' + len);
a();

// new
var newCons = new cons();
newCons.a();
console.log(newCons.b);

function cons() {
  'use strict';
  this.len = 1;
  this.a = function () {
    console.log('a');
  };
  console.log(this, this.a, this.b);
}
cons();